[libcxx-commits] [libcxx] 3a49cff - [libc++] Implement P2445R1 (`std::forward_like`)
Igor Zhukov via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Sep 2 19:22:42 PDT 2022
Author: Igor Zhukov
Date: 2022-09-03T09:17:53+07:00
New Revision: 3a49cffe3add478c2381ed79c56e1e105dd0fa16
URL: https://github.com/llvm/llvm-project/commit/3a49cffe3add478c2381ed79c56e1e105dd0fa16
DIFF: https://github.com/llvm/llvm-project/commit/3a49cffe3add478c2381ed79c56e1e105dd0fa16.diff
LOG: [libc++] Implement P2445R1 (`std::forward_like`)
Co-authored-by: A. Jiang <de34 at live.cn>
Reviewed By: philnik, huixie90, #libc
Differential Revision: https://reviews.llvm.org/D132327
Added:
libcxx/include/__utility/forward_like.h
libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.cpp
libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.pass.cpp
Modified:
libcxx/docs/FeatureTestMacroTable.rst
libcxx/docs/ReleaseNotes.rst
libcxx/docs/Status/Cxx2bPapers.csv
libcxx/include/CMakeLists.txt
libcxx/include/module.modulemap.in
libcxx/include/utility
libcxx/include/version
libcxx/test/libcxx/private_headers.verify.cpp
libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp
libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
libcxx/utils/generate_feature_test_macro_components.py
Removed:
################################################################################
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 0ffd44dbb33c7..88605787ab839 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -314,6 +314,8 @@ Status
------------------------------------------------- -----------------
``__cpp_lib_constexpr_typeinfo`` *unimplemented*
------------------------------------------------- -----------------
+ ``__cpp_lib_forward_like`` ``202207L``
+ ------------------------------------------------- -----------------
``__cpp_lib_invoke_r`` *unimplemented*
------------------------------------------------- -----------------
``__cpp_lib_is_scoped_enum`` ``202011L``
diff --git a/libcxx/docs/ReleaseNotes.rst b/libcxx/docs/ReleaseNotes.rst
index 8d11c1bc2285d..5c1585254d820 100644
--- a/libcxx/docs/ReleaseNotes.rst
+++ b/libcxx/docs/ReleaseNotes.rst
@@ -39,6 +39,7 @@ Implemented Papers
------------------
- P2499R0 - ``string_view`` range constructor should be ``explicit``
- P2417R2 - A more constexpr bitset
+- P2445R1 - ``std::forward_like``
Improvements and New Features
-----------------------------
diff --git a/libcxx/docs/Status/Cxx2bPapers.csv b/libcxx/docs/Status/Cxx2bPapers.csv
index 40a03bb914bf1..cbf0db4bd794e 100644
--- a/libcxx/docs/Status/Cxx2bPapers.csv
+++ b/libcxx/docs/Status/Cxx2bPapers.csv
@@ -72,7 +72,7 @@
"`P2417R2 <https://wg21.link/P2417R2>`__","LWG","A more ``constexpr`` ``bitset``","July 2022","|Complete|","16.0"
"`P2419R2 <https://wg21.link/P2419R2>`__","LWG","Clarify handling of encodings in localized formatting of chrono types","July 2022","",""
"`P2438R2 <https://wg21.link/P2438R2>`__","LWG","``std::string::substr() &&``","July 2022","",""
-"`P2445R1 <https://wg21.link/P2445R1>`__","LWG","``forward_like``","July 2022","",""
+"`P2445R1 <https://wg21.link/P2445R1>`__","LWG","``forward_like``","July 2022","|Complete|","16.0"
"`P2446R2 <https://wg21.link/P2446R2>`__","LWG","``views::as_rvalue``","July 2022","",""
"`P2460R2 <https://wg21.link/P2460R2>`__","LWG","Relax requirements on ``wchar_t`` to match existing practices","July 2022","",""
"`P2465R3 <https://wg21.link/P2465R3>`__","LWG","Standard Library Modules ``std`` and ``std.compat``","July 2022","",""
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index c07497fdc1ae3..e72b42cd5a050 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -649,6 +649,7 @@ set(files
__utility/declval.h
__utility/exchange.h
__utility/forward.h
+ __utility/forward_like.h
__utility/in_place.h
__utility/integer_sequence.h
__utility/move.h
diff --git a/libcxx/include/__utility/forward_like.h b/libcxx/include/__utility/forward_like.h
new file mode 100644
index 0000000000000..780976992b09e
--- /dev/null
+++ b/libcxx/include/__utility/forward_like.h
@@ -0,0 +1,45 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___UTILITY_FORWARD_LIKE_H
+#define _LIBCPP___UTILITY_FORWARD_LIKE_H
+
+#include <__config>
+#include <__type_traits/conditional.h>
+#include <__type_traits/is_const.h>
+#include <__type_traits/is_reference.h>
+#include <__type_traits/remove_reference.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 20
+
+template <class _Ap, class _Bp>
+using _CopyConst = _If<is_const_v<_Ap>, const _Bp, _Bp>;
+
+template <class _Ap, class _Bp>
+using _OverrideRef = _If<is_rvalue_reference_v<_Ap>, remove_reference_t<_Bp>&&, _Bp&>;
+
+template <class _Ap, class _Bp>
+using _ForwardLike = _OverrideRef<_Ap&&, _CopyConst<remove_reference_t<_Ap>, remove_reference_t<_Bp>>>;
+
+template <class _Tp, class _Up>
+[[nodiscard]] constexpr auto forward_like(_Up&& __ux) noexcept -> _ForwardLike<_Tp, _Up> {
+ return static_cast<_ForwardLike<_Tp, _Up>>(__ux);
+}
+
+#endif // _LIBCPP_STD_VER > 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___UTILITY_FORWARD_LIKE_H
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index 5ac7b1c1537c4..e9f8cdc82f558 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1265,6 +1265,7 @@ module std [system] {
module declval { private header "__utility/declval.h" }
module exchange { private header "__utility/exchange.h" }
module forward { private header "__utility/forward.h" }
+ module forward_like { private header "__utility/forward_like.h" }
module in_place { private header "__utility/in_place.h" }
module integer_sequence { private header "__utility/integer_sequence.h" }
module move { private header "__utility/move.h" }
diff --git a/libcxx/include/utility b/libcxx/include/utility
index 9462b833b07c5..d3a9aa492d4e8 100644
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -42,6 +42,10 @@ swap(T (&a)[N], T (&b)[N]) noexcept(noexcept(swap(*a, *b)));
template <class T> T&& forward(typename remove_reference<T>::type& t) noexcept; // constexpr in C++14
template <class T> T&& forward(typename remove_reference<T>::type&& t) noexcept; // constexpr in C++14
+template <typename T>
+[[nodiscard]] constexpr
+auto forward_like(auto&& x) noexcept -> see below; // since C++23
+
template <class T> typename remove_reference<T>::type&& move(T&&) noexcept; // constexpr in C++14
template <class T>
@@ -229,6 +233,7 @@ template <class T>
#include <__utility/declval.h>
#include <__utility/exchange.h>
#include <__utility/forward.h>
+#include <__utility/forward_like.h>
#include <__utility/in_place.h>
#include <__utility/integer_sequence.h>
#include <__utility/move.h>
diff --git a/libcxx/include/version b/libcxx/include/version
index e0c388fc40400..3c24a6d7b9dfb 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -82,6 +82,7 @@ __cpp_lib_execution 201902L <execution>
201603L // C++17
__cpp_lib_filesystem 201703L <filesystem>
__cpp_lib_format 202106L <format>
+__cpp_lib_forward_like 202207L <utility>
__cpp_lib_gcd_lcm 201606L <numeric>
__cpp_lib_generic_associative_lookup 201304L <map> <set>
__cpp_lib_generic_unordered_lookup 201811L <unordered_map> <unordered_set>
@@ -384,6 +385,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_constexpr_bitset 202207L
// # define __cpp_lib_constexpr_cmath 202202L
// # define __cpp_lib_constexpr_typeinfo 202106L
+# define __cpp_lib_forward_like 202207L
// # define __cpp_lib_invoke_r 202106L
# define __cpp_lib_is_scoped_enum 202011L
// # define __cpp_lib_move_only_function 202110L
diff --git a/libcxx/test/libcxx/private_headers.verify.cpp b/libcxx/test/libcxx/private_headers.verify.cpp
index c2c42f785c24b..c822992e38c0a 100644
--- a/libcxx/test/libcxx/private_headers.verify.cpp
+++ b/libcxx/test/libcxx/private_headers.verify.cpp
@@ -660,6 +660,7 @@ END-SCRIPT
#include <__utility/declval.h> // expected-error@*:* {{use of private header from outside its module: '__utility/declval.h'}}
#include <__utility/exchange.h> // expected-error@*:* {{use of private header from outside its module: '__utility/exchange.h'}}
#include <__utility/forward.h> // expected-error@*:* {{use of private header from outside its module: '__utility/forward.h'}}
+#include <__utility/forward_like.h> // expected-error@*:* {{use of private header from outside its module: '__utility/forward_like.h'}}
#include <__utility/in_place.h> // expected-error@*:* {{use of private header from outside its module: '__utility/in_place.h'}}
#include <__utility/integer_sequence.h> // expected-error@*:* {{use of private header from outside its module: '__utility/integer_sequence.h'}}
#include <__utility/move.h> // expected-error@*:* {{use of private header from outside its module: '__utility/move.h'}}
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp
index 96eb793d1d2ef..a4f06bce07cd6 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp
@@ -19,6 +19,7 @@
__cpp_lib_as_const 201510L [C++17]
__cpp_lib_constexpr_utility 201811L [C++20]
__cpp_lib_exchange_function 201304L [C++14]
+ __cpp_lib_forward_like 202207L [C++2b]
__cpp_lib_integer_comparison_functions 202002L [C++20]
__cpp_lib_integer_sequence 201304L [C++14]
__cpp_lib_ranges_zip 202110L [C++2b]
@@ -44,6 +45,10 @@
# error "__cpp_lib_exchange_function should not be defined before c++14"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_integer_comparison_functions
# error "__cpp_lib_integer_comparison_functions should not be defined before c++20"
# endif
@@ -85,6 +90,10 @@
# error "__cpp_lib_exchange_function should have the value 201304L in c++14"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_integer_comparison_functions
# error "__cpp_lib_integer_comparison_functions should not be defined before c++20"
# endif
@@ -135,6 +144,10 @@
# error "__cpp_lib_exchange_function should have the value 201304L in c++17"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_integer_comparison_functions
# error "__cpp_lib_integer_comparison_functions should not be defined before c++20"
# endif
@@ -188,6 +201,10 @@
# error "__cpp_lib_exchange_function should have the value 201304L in c++20"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_integer_comparison_functions
# error "__cpp_lib_integer_comparison_functions should be defined in c++20"
# endif
@@ -244,6 +261,13 @@
# error "__cpp_lib_exchange_function should have the value 201304L in c++2b"
# endif
+# ifndef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should be defined in c++2b"
+# endif
+# if __cpp_lib_forward_like != 202207L
+# error "__cpp_lib_forward_like should have the value 202207L in c++2b"
+# endif
+
# ifndef __cpp_lib_integer_comparison_functions
# error "__cpp_lib_integer_comparison_functions should be defined in c++2b"
# endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index 8eaab46e0e5ef..d3ac7b7dc002d 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -76,6 +76,7 @@
201902L [C++20]
__cpp_lib_filesystem 201703L [C++17]
__cpp_lib_format 202106L [C++20]
+ __cpp_lib_forward_like 202207L [C++2b]
__cpp_lib_gcd_lcm 201606L [C++17]
__cpp_lib_generic_associative_lookup 201304L [C++14]
__cpp_lib_generic_unordered_lookup 201811L [C++20]
@@ -417,6 +418,10 @@
# error "__cpp_lib_format should not be defined before c++20"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_gcd_lcm
# error "__cpp_lib_gcd_lcm should not be defined before c++17"
# endif
@@ -1052,6 +1057,10 @@
# error "__cpp_lib_format should not be defined before c++20"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_gcd_lcm
# error "__cpp_lib_gcd_lcm should not be defined before c++17"
# endif
@@ -1801,6 +1810,10 @@
# error "__cpp_lib_format should not be defined before c++20"
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_gcd_lcm
# error "__cpp_lib_gcd_lcm should be defined in c++17"
# endif
@@ -2847,6 +2860,10 @@
# endif
# endif
+# ifdef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_gcd_lcm
# error "__cpp_lib_gcd_lcm should be defined in c++20"
# endif
@@ -4085,6 +4102,13 @@
# endif
# endif
+# ifndef __cpp_lib_forward_like
+# error "__cpp_lib_forward_like should be defined in c++2b"
+# endif
+# if __cpp_lib_forward_like != 202207L
+# error "__cpp_lib_forward_like should have the value 202207L in c++2b"
+# endif
+
# ifndef __cpp_lib_gcd_lcm
# error "__cpp_lib_gcd_lcm should be defined in c++2b"
# endif
diff --git a/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.cpp b/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.cpp
new file mode 100644
index 0000000000000..f010e7cb674b6
--- /dev/null
+++ b/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.cpp
@@ -0,0 +1,111 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cassert>
+#include <type_traits>
+#include <utility>
+
+using namespace std;
+
+struct U {}; // class type so const-qualification is not stripped from a prvalue
+using CU = const U;
+using T = int;
+using CT = const T;
+
+U u{};
+const U& cu = u;
+
+static_assert(is_same_v<decltype(forward_like<T>(U{})), U&&>);
+static_assert(is_same_v<decltype(forward_like<T>(CU{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<T>(u)), U&&>);
+static_assert(is_same_v<decltype(forward_like<T>(cu)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<T>(std::move(u))), U&&>);
+static_assert(is_same_v<decltype(forward_like<T>(std::move(cu))), CU&&>);
+
+static_assert(is_same_v<decltype(forward_like<CT>(U{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT>(CU{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT>(u)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT>(cu)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT>(std::move(u))), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT>(std::move(cu))), CU&&>);
+
+static_assert(is_same_v<decltype(forward_like<T&>(U{})), U&>);
+static_assert(is_same_v<decltype(forward_like<T&>(CU{})), CU&>);
+static_assert(is_same_v<decltype(forward_like<T&>(u)), U&>);
+static_assert(is_same_v<decltype(forward_like<T&>(cu)), CU&>);
+static_assert(is_same_v<decltype(forward_like<T&>(std::move(u))), U&>);
+static_assert(is_same_v<decltype(forward_like<T&>(std::move(cu))), CU&>);
+
+static_assert(is_same_v<decltype(forward_like<CT&>(U{})), CU&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(CU{})), CU&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(u)), CU&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(cu)), CU&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(std::move(u))), CU&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(std::move(cu))), CU&>);
+
+static_assert(is_same_v<decltype(forward_like<T&&>(U{})), U&&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(CU{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(u)), U&&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(cu)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(std::move(u))), U&&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(std::move(cu))), CU&&>);
+
+static_assert(is_same_v<decltype(forward_like<CT&&>(U{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT&&>(CU{})), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT&&>(u)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT&&>(cu)), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT&&>(std::move(u))), CU&&>);
+static_assert(is_same_v<decltype(forward_like<CT&&>(std::move(cu))), CU&&>);
+
+static_assert(noexcept(forward_like<T>(u)));
+
+static_assert(is_same_v<decltype(forward_like<U&>(u)), U&>);
+static_assert(is_same_v<decltype(forward_like<CU&>(cu)), CU&>);
+static_assert(is_same_v<decltype(forward_like<U&&>(std::move(u))), U&&>);
+static_assert(is_same_v<decltype(forward_like<CU&&>(std::move(cu))), CU&&>);
+
+struct NoCtorCopyMove {
+ NoCtorCopyMove() = delete;
+ NoCtorCopyMove(const NoCtorCopyMove&) = delete;
+ NoCtorCopyMove(NoCtorCopyMove&&) = delete;
+};
+
+static_assert(is_same_v<decltype(forward_like<CT&&>(declval<NoCtorCopyMove>())), const NoCtorCopyMove&&>);
+static_assert(is_same_v<decltype(forward_like<CT&>(declval<NoCtorCopyMove>())), const NoCtorCopyMove&>);
+static_assert(is_same_v<decltype(forward_like<T&&>(declval<NoCtorCopyMove>())), NoCtorCopyMove&&>);
+static_assert(is_same_v<decltype(forward_like<T&>(declval<NoCtorCopyMove>())), NoCtorCopyMove&>);
+
+static_assert(noexcept(forward_like<T>(declval<NoCtorCopyMove>())));
+
+constexpr bool test() {
+ {
+ int val = 1729;
+ auto&& result = forward_like<const double&>(val);
+ static_assert(is_same_v<decltype(result), const int&>);
+ assert(&result == &val);
+ }
+ {
+ int val = 1729;
+ auto&& result = forward_like<double&>(val);
+ static_assert(is_same_v<decltype(result), int&>);
+ assert(&result == &val);
+ }
+ {
+ int val = 1729;
+ auto&& result = forward_like<const double&&>(val);
+ static_assert(is_same_v<decltype(result), const int&&>);
+ assert(&result == &val);
+ }
+ {
+ int val = 1729;
+ auto&& result = forward_like<double&&>(val);
+ static_assert(is_same_v<decltype(result), int&&>);
+ assert(&result == &val);
+ }
+ return true;
+}
+
+int main() {
+ assert(test());
+ static_assert(test());
+}
diff --git a/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.pass.cpp b/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.pass.cpp
new file mode 100644
index 0000000000000..629d82fcfd79d
--- /dev/null
+++ b/libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.pass.cpp
@@ -0,0 +1,13 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// Includes Microsoft's test that tests the entire header.
+
+#include "test.cpp"
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 27e2d23f7da66..38b04d261e484 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -322,6 +322,10 @@ def add_version_header(tc):
"headers": ["format"],
"test_suite_guard": "!defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)",
"libcxx_guard": "!defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)",
+ }, {
+ "name": "__cpp_lib_forward_like",
+ "values": { "c++2b": 202207 },
+ "headers": ["utility"],
}, {
"name": "__cpp_lib_gcd_lcm",
"values": { "c++17": 201606 },
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